Use a bezier timing function for the overview mode animation

ui/gfx/animation/tween.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_ANIMATION_TWEEN_H_
 #define UI_GFX_ANIMATION_TWEEN_H_
 
 #include "base/basictypes.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/gfx_export.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 
 namespace gfx {
 
 class GFX_EXPORT Tween {
  public:
   enum Type {
-    LINEAR,        // Linear.
-    EASE_OUT,      // Fast in, slow out (default).
-    EASE_IN,       // Slow in, fast out.
-    EASE_IN_2,     // Variant of EASE_IN that starts out slower.
-    EASE_IN_OUT,   // Slow in and out, fast in the middle.
-    FAST_IN_OUT,   // Fast in and out, slow in the middle.
-    EASE_OUT_SNAP, // Fast in, slow out, snap to final value.
-    SMOOTH_IN_OUT, // Smooth, consistent speeds in and out (sine wave).
-    ZERO,          // Returns a value of 0 always.
+    LINEAR,           // Linear.
+    EASE_OUT,         // Fast in, slow out (default).
+    EASE_OUT_BEZIER,  // Variant of EASE_OUT that starts and ends slower.
+    EASE_IN,          // Slow in, fast out.
+    EASE_IN_2,        // Variant of EASE_IN that starts out slower.
+    EASE_IN_BEZIER,   // Variant of EASE_IN that starts slower than EASE_IN and
+                      // ends faster than both EASE_IN and EASE_IN_2
+    EASE_IN_OUT,      // Slow in and out, fast in the middle.
+    FAST_IN_OUT,      // Fast in and out, slow in the middle.
+    EASE_OUT_SNAP,    // Fast in, slow out, snap to final value.
+    SMOOTH_IN_OUT,    // Smooth, consistent speeds in and out (sine wave).
+    ZERO,             // Returns a value of 0 always.
   };
 
   // Returns the value based on the tween type. |state| is from 0-1.
   static double CalculateValue(Type type, double state);
 
   // Conveniences for getting a value between a start and end point.
   static SkColor ColorValueBetween(double value, SkColor start, SkColor target);
   static double DoubleValueBetween(double value, double start, double target);
   static float FloatValueBetween(double value, float start, float target);
 
@@ skipping 18 matching lines @@
  private:
   Tween();
   ~Tween();
 
   DISALLOW_COPY_AND_ASSIGN(Tween);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_ANIMATION_TWEEN_H_